.gallery-container   {
    .gallery-item    {
        display: inline-block;
        width: 33.33333%;   
        float: left;
        overflow: hidden;
        
        @media (max-width: 1200px) {
            width: 50%;   
        }
        
        @media (max-width: 600px) {
            width: 100%;   
        }
        
        .image-wrapper   {
            width: 100%;
            padding-top: 60%;
            img {
                display: block;
                position: absolute;
                top: 0;
                left: 0;
                width: 100%;
            }   
        }
    }
}